Centrifugal pump for liquid



Aug. 7, 1945. G. c. MEREDEW ETAL CENTRIFUGAL PUMP FOR LIQUID 4 Sheets-Sheet 1 Filed June 17, 1943 aha 4 fir/M rs Aug.7, 1945. G. c. MEREDEW ETA]. 2,381,834

CENTRIFUGAL PUMP FOR LIQUID Filed June 17, 1943 4 Sheets-Sheet 2 Zinnfin: I I

Aug. 7, 1945. G. c. MEREDEW ETAL 2,381,834

CENTRIFUGAL PUMP FOR LIQUID Filed June 17, 1943 4 Sheets-Sheet 5 f Vii r m 41 433W Aug. 7, 1945. G. c. MEREDEW ETAL CENTBIFUGAL PUMP FOR LIQUID 4 Sheets-Sheet 4 Filed June '17, 1945 e 6'. r ya 6%,

clearance.

Patented Aug. 7, 1945 CENTRIFUGAL PUMP FOR LIQUID George Charles Meredew and Arthur Lionel BrownDawson, London, England, assignors to Self-Priming Pump & Engineering Co. Limited, London, England, a British company Application June 17, 1943, Serial No. 491,184 In Great Britain April 20, 1942 4 Claims.

This invention relates to motor-driven centrifugal pumps for pumping liquid and of the type (hereinafter referred to as the type described) in which the driving motor, usually an electric motor, and a direct-coupled pump impeller form a unit which is removably mounted in a base-casting which provides inlet and outlet conduits for the liquid.

In pumps of the type described it has been usual to form the annular wall of the impeller chamber which defines the inlet throat of the chamber as part of the base-casting. With such an arrangement motor units have not been readily interchangeable because of the difliculty of ensuring that, on assembly of a motor-impeller unit on the base-casting the proper clearance will be provided between the impeller blades and the co-operating annular wall.

According to present invention the above difficulties are avoided by forming the whole impeller chamber including the annular inlet wall as part of the motor-impeller unit. The impeller chamber and outlet flow passages may be formed in a block which is bolted to the impeller-end of the motor housing Preferably the annular inlet wall of the impeller chamber, or that portion of it which defines the inlet throat, is formed as a removable insert in the block, for example is screwthreaded into the block, so that the assembly may be easily and accurately adjusted to the proper throat Alternatively, that portion of the annular wall of the impeller chamber which defines the inlet throat is formed as a removable annular disc secured in position by the same bolts which hold the aforesaid block to the impellerend of the motor housing.

The invention is particularly (but not exclusively) concerned with the pressure feeding by means of centrifugal pumps of the type described of petrol or other liquid fuel to internal-combustion engines especially aircraft engines. In such cases the inlet conduit of the base-casting is arranged in communication with the lower end of the fuel tank and the outlet conduit is arranged to deliver to the carburettor system.

Two examples according to the invention will now be described with reference to the accompanying drawings, in which- Figure 1 is a side elevation of the pump according to the first example, the base-casting portion of the pump assembly being shown in section;

Figure 2 is a cross-section of the base-casting portion of the pump shown in Figure 1, taken at right-angles to that figure;

Figure 3 is a longitudinal central cross-section of the pump according to the second example;

Figure 4 is a longitudinal cross-section, at right-angles to Figure 3, showing the base-casting portion of the pump, and

Figure 5 is a plan view of the pump shown in Figure-3.

Like reference numerals indicate like parts in the various figures.

' Referring, in the first place, to Figures 1 and 2, the pump there illustrated is designed for the pressure feeding of petrol or other liquid fuel from a storage tank to the carburettor system of an internal-combustion engine installation for use in aircraft, or for the transference of fuel from one storage tank to another on an aircraft. The pump comprises a base-casting l0 which provides a fuel inlet conduit ii and two diametrically opposed fuel outlet conduits it. The base-casting is adapted to be bolted directly to the bottom of the fuel tank l3, indicated in chain lines in Figure 1. For this purpose the inlet conduit is formed with a spigot portion H for insertion in an aperture in the bottom of the fuel tank i3 and with a flange l5 surrounding the spigot and adapted to be secured by bolting to the bottom of the tank.

The base-casting I0 is formed with an integral trunk portion 56 arranged to receive the.

removable motor impeller unit. The removable unit comprises a housing I! containing the driving motor it and impeller 19 direct-coupled to the motor shaft 20 which is suitably journalled in end bearings, one of which is shown at 2i in Figure 1. The impeller end of the motor shaft extends through a liquid sealing gland 22 of any suitable type.

The impeller chamber 23 and fiow passages 24 leading outwardly therefrom are formed in a block 25 which is secured by bolts 26 to the. impeller end of the motor housing ll. The annular inlet wall of the impeller chamber which defines the inlet throat is formed as a removable insert 21 screw-threaded into the lower end of the block 25. With this provision the insert 21 may be accurately adjusted, by rotation relatively to the block, to give the desired throat clearance.

The motor impeller unit is sealed in the trunk portion l6 of the baseecasting in the following way. The block 25 which is bolted to the imbolt heads.

peller end of the motor housing is formed with an extended annular wall 28 which fits within the trunk l6 and which has a flange 29 adapted to bear, with an annular packing ring 30 interposed, on the outer end of the base-casting trunk. A packing ring ll inset at the inner end of the block 25 is also provided. The motor impeller unit is held to the base-casting by means of a nut 32 screwthreaded to the trunk l4 and provided with a bezel ring 33 arranged to engage over the afore-mentioned flange 29 on the extended annular wall 28 of the'impeller casin block.

The base-casting also embodies a by-pass 34 between the inlet and outlet conduits H, II controlled by a suction valve 35 so arranged that in the event of a failure of the motor impeller unit or in any circumstances in which that unit may be inoperative the induction pullof the engine will open the valve 35 and take the fuel supply through the by-pass conduit 34, thus short-circuiting the flow through the impeller chamber 23 and eliminating the resistance which would thereby be imposed when the impeller is stationary. Any suitable form of valve, which may be other than the particular type illustrated, may, of course, be used for controlling the by-pass conduit. Similarly, means, other than that illustrated. may be employed for securing the removable motor impeller unit to the base-casting.

In the second example, shown in Figures 3, 4 and 5, the pump again comprises a base-casting III which is adapted to be secured to the bottom wall l3 of the fuel tank. For this purpose the base-casting is provided with a flange 4| arranged to be secured by bolts to the bottom wall l3 around an aperture 42 therein. As before the base-casting is provided with a trunk portion l6 within which the inner end of the removable motor impeller unit is received. A slightly different method of securing the motor impeller unit in place is employed. The motor housing is formed with a circumferential flange 43, the inner face of which is arranged to seat on the outer end of the base-casting trunk IS, with a packing ring 44 interposed between them. The outer face of the flange 43 is arranged to be engaged by a bezel ring 33 formed on a nut 32 in screwthreaded engagement with the outer end of the trunk It. The impeller chamber is, as before, formed in a block 25 which is secured by bolts 26 to the impeller end of the motor housing. In place of a screwthreaded insert (as used in the first examplel defining the inlet throat of the impeller chamber, this is now formed by an annular member 45 which is held in place by the bolts 26 which secure the block 25 to the impeller end of the removable unit. For this purpose the member 45 is formed with a flange 46 which is apertured to receive the bolts 26. The throat member 45 is removable independently of the block 25 in the following way. Each of the bolt apertures in the throat member is in the form of a slot 41, 48 (see Figure one end 41 of which provides for a close fit round the stem of the bolt and the other end 48 of which is of sufficiently large dimensions to pass the head of the bolt. In the normal, i. e., secured, position of the throat member the securing bolts 26 are located within the narrow ends 41 of the slots, and the member is thus held in position by the When it is desired to remove the throat member the bolts are slackened oil slightly and the member is partially rotated to bring the large slot ends 48 into register with the bolt heads. The member 45 is then free to be withdrawn in an axial direction. In order to eilect adjustment of the throat clearance one or more shims 49 may be inserted between the flange 40 of the throat member and the end face of the block 25. Preferably each shim is in the form of an annulus having the same internal and external diameters as the corresponding dimensions of the end face of the block 25, and having slotted bolt apertures corresponding to the slots 41, 4B in the flange 48 of the throat member.

As before, the impeller end of the motor shaft 20 extends through a liquid sealing gland 22, and in this case provision is made for draining the gland through conduits It in the impeller end of the motor housing and registering conduits 6| in the trunk portion of the base-casting.

As before. the base-casting embodies a suction-valve-controlled by-pass 34 between the inlet and outlet liquid conduits H, l2.

In order to seal the inlet conduit ll of the base-casting against entry of liquid fuel from the tank when the motor impeller unit is withdrawn for replacement, inspection or repair, a manually operable flap valve or like closure device (not shown) may be associated with the base-casting so that the inlet conduit may readily be sealed before the removable motor unit is withdrawn.

While in the foregoing examples an electric motor is used as the driving means in the motor impeller unit, it is to be understood that the invention may equally well be embodied in pumps of the type described in which other motors, for example pneumatically driven motors, are employed,

In the foregoing examples, the base -casting has been shown as fixed to the bottom of the fuel tank and this is the normally preferred arrangement. It is to be understood, however, that if desired the base-casting may be secured to the side wall of the tank near its lower end and the arrangement may be such that the pump unit as a whole extends vertically, longitudinally or at any convenient angle in relation to the tank.

We claim:

1. A motor-driven centrifugal pump for liquid comprising in combination base casting providing inlet and outlet conduits for liquid, a motor housing, a driving motor located therein and a direct-coupled pump impeller, the housing, motor and impeller together forming a unit removably mounted in the base casting, a block which provides the impeller chamber and which is secured by bolts to the impeller end of the motor housing so as to form part of the removable motor impeller unit, and an annular disc defining the inlet throat of the impeller chamber and secured to the block aforesaid by the same bolts which hold the block to the impeller end of the motor housing, the annular disc being provided with slotted apertures to enable the disc, on partial rotation in relation to the block, to be removed on slackening of the securing bolts, without necessitating complete withdrawal thereof.

2. A motor-driven centrifugal pump for liquid comprising in combination a base casting providing inlet and outlet conduits for liquid, a motor housing, a driving motor located therein and a direct-coupled pump impeller, the housing, motor and impeller together forming a unit removably mounted in the base casting, and a block secured by bolts to the impeller end of the motor housing and providing an impeller chamber, the

whole of which including an annular wall defining the inlet throat of the chamber constitutes part of the removable motor-impeller unit, the aforesaid inlet-throat wall being formed as a removable annular disc secured in position by the same bolts which hold the block aforesaid in the impeller end of the motor housing.

3. A centrifugal pum according to claim 2 in which the base casting is formed with an integral hollow trunk and the impeller chamber block is formed with an extended annular wall which is fitted within the trunk and which has a flange adapted to bear, with an annular packing interposed, on the outer end of the trunk,

the motor-impeller unit being held to the base casting by a nut screwthreaded to the trunk and provided with a bezel ring engaging over the aforesaid flange on the extended annular wall of the impeller chamber block.

4. A centrifugal pump according to claim 2 in which the base casting is formed with a trunk portion in which the impeller end of the removable motor-impeller unit is received, the motor housing being formed with a circumferential flange, the inner face of which is arranged to seat, with an annular packing interposed, on the outer end of the base casting trunk, while the outer face of the flange is engaged by a ring formed on a nut in screwthreaded engagement with the outer end of the trunk.

GEORGE CHARLES MEREDEW. ARTHUR LIONEL BROWN DAWSON. 

